New fluorine-containing compounds



United States Patent NEW FLUORINE-CONTAINJNG COMPOUNDS Herbert Aubrey Stevenson and Nigel George Clark, Nottingham, England, John E. Cranham, Accra, Ghana, and Dennis John Higgons, Nottingham, England, assignors to Boots Pure Drug Company Limited, Nottingham, England, a British company No Drawing. Filed Nov. 4, 1957, Ser. No. 694,085 Claims priority, application Great Britain Mar. 2, 1953 13 Claims. (Cl. 167-30) This invention relates to new fluorine-containing compounds and compositions thereof which have been found to possess valuable properties and is a continuation-inpart of our US. application Serial No. 412,121, filed February 23, 1954, now abandoned.

This invention consists in the compound p-chlorobenzyl p-fluorophenyl sulphide and in compositions containing it which may be employed in the control of eggs and active stages of mites (Acari) in particular the plant feeding Tetranychidae or red spider mites e.g. Tetymnychus telarius L. and Metatetranychus zzlmi Koch. The compound of the invention may be prepared by reaction of p-fluorobenzenethiol with a p-chlorobenzyl halide in the presence of an alkaline condensing .agent such as sodium alkoxide, if the reaction is performed under anhydrous conditions, or an alkali metal hydroxide if water is present.

The compound of the invention possesses activity against the above named mites which is of the same order as that of the known acaricide, p-chlorobenzyl p-chlorophenyl sulphide but possesses physical properties which enable it to be used in certain types of formulations in Which the known acaricide cannot be used conveniently. Thus the volatility of the known acaricide p-chlorobenzyl p-chlorophenylsulphide is of a low order and it has not proved possible to disperse this compound in the form of a vapour either by direct heating of the compound or formulation in smoke-generating compositions of the type normally employed in horticulture. Further due to the low solubility of p-chlorobenzyl p-chlorophenylsulphide in solvents normally employed in the generation of aerosols without mechanical assistance it has not been possible to disperse the compound in a satisfactory manner by such means. The compound of the present invention however possesses a vapour pressure which is approximately 20 times as great as that of the above compound at 20 C. and approximately times as great at 60 C. The data for the vapour pressure of the two compounds other pesticides, such as DDT, benzene hexachloride,

Vapour pressure (mm. Hg)

Temperature p-Chlorobenzyl p-fiuorophenylsulphide Because of the much higher volatility of the compound of the present invention it is possible to disperse the compound in the form of a vapour either by direct heating or by formulation in smoke generating compositions. Further the compound of the invention has been found 2,938,829 Patented May 31, 1960 See in the generation of pesticidal aerosols and can be dispersed readily in this form. In view of these properties, i.e. ready dispersal as a smoke of aerosol, the compound of the invention is particularly valuable for the treatment of infestations of acari which occur in glasshouse in crops such as tomatoes, etc. The finding of these properties is both unexpected and valuable.

Accordingly the present invention is particularly concerned with compositions which are suitable for generating p-chlorobenzyl p-fluorophenylsulphide in the form of a smoke or aerosol.

Methods of producing smokes, i.e. a particulate cloud or vapour cloud of the active material, are well-known in the art and such methods can be successfully applied to the production of smokes containing p-chlorobenzyl p-fiuorophenylsulphide. Thus the compound may be heated on open trays within the enclosed area to be treated and may be completely vapourised'thereby without substantial decomposition. Alternatively the compound may be placed in the inner compartment of a dual compartment canister which contains a chemical fuel in the outer container. Before use the top of the inner compartment may be removed to give access to the outer atmosphere and the chemical fuel may then be ignited by means of a fuse. The heat thereby generated causes the volatilisation of the active compound into the enclosed area to be treated. As a further alternative the active compound of the invention may beadmixed with a heater composition, such that the active compound is generated as a smoke on ignition. Some difliculty is encountered in formulating such compositions in view of the low melting point of the active compound. Thus the'compound, when present in such mixtures, tends to melt if exposed to elevated temperatures during storage and to flow to the base of the container in which the composition is packed thereby forming unsatisfactory or even dangerous compositions. This difiiculty can be overcome in a convenient manner by absorbing the active compound on a highly porous inert diluent and using the resulting product in the smoke generating composition. A diluent which we have found to be suitable for such purpose is a finely divided silicic acid of high absorptive capacity which is available under the proprietary name of Aerosil. The heater compositions which are employed in the preparation of the smoke generating compositions may comprise in admixture a combustible substance, for example hexamine, a substance which readily liberates oxygen, for example potassium chlorate, an inert substance, for example talc or a suitable diatomaceous earth, and a dampening agent, for example hexachloroethane which serves to prevent too rapid combustion and thus decomposition of the active compound. Alternatively the heater composition may comprise a carbohydrate such as sucrose or a polyhydric alcohol such as sorbitol or mannitol, and potassium chlorate. Heater compositions of this character are well known and are used in association with other pesticides, such as DDT, benzene hexachloride, and azobenzene to form smoke generating compositions containing these pesticides for horticultural and other uses. In forming the smoke generating compositions, the active compound, preferably adsorbed on a diluent such as finely divided silicic acid as described above, is admixed with the heater composition and the mixture is charged into a container or is formed into pelletswhich on ignition emit a smoke containing the active compound as a vapour.

In the preparation of compositions suitable, for dispen sion as aerosols which contain'p-chlorobenzyl p-fluoro phenylsulphide as active ingredient, the latter compound to be highly soluble in the solvents normally employed may be dissolved in avolatile solvent such as acetone. The resulting solution may then be dispersed 'mechanical ly, for example using a paint spray gun to produce the aerosol. Although this method of producing aerosols is perfectly satisfactory as far as control of red spider is concerned it is a much less attractive method commercially than those which will now be dmcribed. Alternatively and preferably the active compound may be dissolved in' a high boiling aromatic solvent such as xylene or a non-volatile oil such as a vegetable oil together with a supplementary solvent such as cyclohexanone or acetone if desired. Such compositions are readily dispersed as aerosols by mechanical means or by incorporating therein; avolatile propellant such as Freon (a mixture of .chloro fluoro derivativesof methane and ethane). Where a volatile propellant is employed it is necessary to enclose the composition in a suitable pressurized container fitted with a valve from which the composition can be released as an aerosol when required. As mentioned briefly above the solubility of p-chlorophenyl p-chlorobenzylsulphide in solvents such as xylene and Freon is so-low that, the compound cannot be employed in such formulations as those described above for self-propelling aerosols.

In order to obtain effective control of red spider mite infestations in glasshouses and other-enclosed areas by the release of p-chlorobenzyl p-fluorophenylsulphide therein in the form of a smoke or aerosol it is desirable that'the compound be dispersed at a rate of the order of 2 grams per 1000 cu. ft. Concentrations aslow as 1 gram per 1000 cu. ft. have proved effective in many cases but theuse of the higher dosage rate ensures complete success in the control of the red spider mite.

Red spider mite infestations on the following plants can be successfully controlled by the use of p-chlorobenzyl p-fluorophenylsulphide without damage to the plant: Tomatoes, roses, hydrangeas, Chrysanthemums, cherry, plum, beans, pelargonium, gravillea, gloxinia, brophyllum, solanum capsicastrum, kochia, celosia, asparagus, pluosa, strawberries.

- The following non-limitative example illustrate the invention.

' Example 1 In the preparation of p-chlorobenzyl p-fluorophenylsulphide'09 gram of sodium is dissolved in a mixture of 5 grams of pffluorothiophenol and 25 cc. of anhydrous ethanol. To the solution is added 6.4 grams of p-chlorobenzylchloride and the mixture is heated under reflux for130 minutes. After cooling, the product is poured into 150 cc. ofwater. The solid which separates is isolated by filtration and recrystallised twice from aqueous 'eth- :anol, There is thus obtained pchlorobenzyl p-fluorophenylsulphide in the form of a colourless crystalline solid which has a melting point of 34.5'35.5 C. [Found C, 62.0 H, 4.0. C H ClF requires C, 61.8; H, 4.0%.]

Example 2 A composition suitable for the preparation of an aerosol is obtained by dissolving 200 grams of p-chlorobenzyl p-fluorophenylsulphide in a 1:1 mixture of Teaseed oil and cyclohexanone and diluting the solution to 350 cc. by the addition of a suitable quantity of'the' same mixture. The solution so obtained may be treated in one of two ways.

(a) 150 cc. of the solution is diluted to 900 cc. by the addition of acetone and the mixture is dispersed as an aerosol by the use of a paint spray gun so' as to obtain within the area to be treated a concentration within the range of 1 to 2 grams of active ingredient per 1000 cu. ft.

((2') 175 cc. of thesolution and 1170 grams of Freon 12'.v (dichlorodifluoromethane) are filled under pressure ina compressed gas cylinder from which the composition is dispersed as an aerosol so as to obtain within the area to be treated a concentration of '1: to 2 grams of active ingredient per 1000 cu. ft. i

, e I Example 3 A-composition suitable for thepreparationof an aero sol: isv prepared by dissolving 1 00 grams. of: p-chloro 4 benzyl p-fluorophenylsulphide in 100 cc. of xylene. 55 grams of the solution so obtained and 155 grams of Freon 12 plus 155 grams of Freon 11 are filled under pressure in a finger tip dispenser from which the composition is dispersed as an aerosol so as to obtain within the area to be treated a concentration of 1 to 2 grams of active ingredient per 1000 cu. ft. H

In laboratory tests with an aerosol produced using the above composition, small French bean leaves were infested with the eggs of T. telarius L. by allowing adult female mites to remain on the leaves until they had laid 3050 eggs per leaf, and then removing them. Egg batches? at the time of treatment were 1-2 days .old. Treatment was carried out by space fumigation of glasshouses with the leaves distributed in the glasshouses using aerosols produced by the above method at a concentration of 1 gram and 2 grams of active compound per 1000 cu. ft. After 4 hours in the glasshouse the leaves were stored in a constant temperature room at F. and 60% relative humidity under artificial light. Assessment of effect on eggs and young mites was carried out 7 days after treatment at which time the batch ofeggs was complete and all young mites had developed into nymphs on the untreated controls. A count was made of unhatched eggs, dead young mites, and live young mites and from this it was possible to calculate the percentage kill of eggs alone and of eggs plus young mites. The results of a number of separate treatments with pchlorobenzyl p-fluorophenyl-sulphide are recorded in the following table:

Percent kill Percent kill Rate of application, gm./1,000 cu. ft. of eggs of eggsplus V young mites The composition described in the above example has been subjected to field trials on a wide scale. In a typical trial the composition was dispersed at a rate of 2 grams per 1000 cu. ft. in a glasshouse of capacity 18,000 cu. ft'. containing tomatoes bearing a heavy infestation of red spider mite. The leaves of the tomato plants were sampled before and at intervals after treatment and it was found that 8 days after treatment the reduction in all stages of the mite alive on the plants was 99.9% and 21 days after treatment was still 99.9%.

Example 4 In the preparation of a composition suitable for generating a smoke containing p-chlorobenzyl p-fluorophenyl sulphide, a mixture of 6 grams of Aerosil (a proprietary brand of silicic acid of high absorptive capacity) and 34 grams 'of p-chlorobenzyl p-fluorophenylsulphide is ground to form an intimate mixture. To the mixture is added 21 grams of sucrose and 19 grams of kaolin and the product is again subject to grinding to ensure intimate mixture. To the resulting product is added 20 grams of potassium chlorate which has been pulverised independently and the mixture so obtained is filled under pressure into a'container provided with a fuse system to 5 rate of 1-2 grams of the latter per 1000 cu. ft. of the area treated.

3. A process according to claim 2 in which the plants are treated with p-chlorobenzyl p-fiuorophenylsulphide by volatilisation of the latter compound.

4. A process according to claim 2 in which the p-chlorobenzyl p-fluorophenylsulphide is applied to the plants in the form of a smoke by igniting a mixture of p-chlorobenzyl p-fiuorophenylsulphide and a heater composition.

5. A process according to claim 2 in which the p-chlorobenzyl p-fiuoroph enylsulphide is applied to the plants in the form of an aerosol.

6. A process according to claim 5 in which the aerosol is generated by dissolving p-chlorobenzyl p-fiuorophenylsulphide in a volatile solvent and dispersing mechanically the solution so obtained.

7. A process according to claim 5 in which the aerosol is generated by dissolving p-chlorobenzyl p-fiuorophenylsulphide in a non-volatile solvent and dispersing mechanically the solution so obtained.

8. A process according to claim 5 in which the aerosol is generated by dissolving pchlorobenzyl p-fluorophenylsulphide in a non-volatile solvent and dispersing the solution so obtained by means of a volatile propellant.

9. An acaricidal composition comprising an acaricidal adjuvant as a carrier and p-chlorobenzyl p-fiuorophenylsulphide as the essential active acaricidal ingredient.

10. An acaricidal composition according to claim 9 in which said carrier is a heater composition.

11. An acaricidal composition according to claim 9 in which said carrier is a volatile solvent.

12. An acaricidal compostion according to claim 9 in which said carrier is a non-volatile solvent.

13. An acaricidal composition according to claim 9 in which said carrier is a non-volatile solvent and a volatile propellant.

March et al.: J. Econ. Ent., 45, 851-860 (1952).

Cranham: Chem. and Ind., Nov. 7, 1953, pp. 1206- 1207.

Frear: Chem. of Instecticides, Fungicides and Herbicides, 2nd ed., 1948, pp. 5-6. 

2. A PROCESS FOR THE CONTROL OF INFESTATIONS OF THE EGGS AND ACTIVE STAGES OF RED SPIDER MITES ON GROWING PLANTS IN AN ENCLOSED AREA WHICH COMPRISES TREATING THE PLANTS WITH P-CHLOROBENZYL P-FLUOROPHENYLSULPHIDE AT A RATE OF 1-2 GRAMS OF THE LATER PER 1000 CU. FT. OF THE AREA TREATED. 